1. Field of the Invention
The present invention is in the field of destruction of organic waste and pollutants. More particularly the present invention is in the field of methods and systems for low temperature degradation of organic matter, particularly soot and other organic materials from diesel engine exhaust and other fossil fuel sources, medical wastes, animal corpses and other organic materials without the use of burning, incineration, or any form of high temperature combustion.
2. Review of the Relevant Technologies
Modern society has mastered the art of producing new goods but struggles to dispose of its wastes. While recycling can reduce the overall waste stream, there is still a huge amount of waste that simply does not lend itself to be recycled. The United States generates approximately 180,000,000 pounds of municipal solid waste every year, most of which is disposed in landfills. However, landfills are becoming a scarce commodity. The EPA has estimated that 90% of the country's existing landfills will reach capacity within the next decade. Because of increasing public protest and "not in my backyard" opposition, opening new landfill sites has become very difficult, increasing their cost and decreasing the number of new sites being constructed.
Most conventional thinking regarding the destruction of industrial, medical or municipal waste has revolved around some form of combustion, incineration or other extreme temperature solution. Because of the complexities and high temperatures utilized, these systems are expensive, must be centrally located, and are operated by highly trained technicians. While combustion, burning or incineration has proven effective in reducing the overall weight and volume of many wastes, these methods have not provided a truly effective solution to our society's current waste management problems. Because of the need to centrally locate combustion, burning or incineration systems, waste materials must be picked up, delivered and then destroyed at the central site. However, just as landfills are becoming increasing difficult to open, incinerators have faced even greater opposition due to the perception that they are heavy polluters. This means that the use of incinerators as the means to effectively reduce the waste crises will ultimately fail.
The disposal of medical waste and other infectious materials in a manner that will not release dangerous pathogenic or disease-causing agents into the environment has always been a relatively expensive and difficult task. This is because it is necessary to first kill all pathogenic or potentially pathogenic agents, and then completely destroy the tissue to prevent further rotting and decay of the tissue. Otherwise, the tissue can provide a haven where later-introduced foreign pathogenic agents can thrive. For instance, it is inadequate to simply sterilize once-living human tissue and then dispose of it like ordinary refuse where it will be exposed to bacteria or other natural biodegradation agents. In the process of natural degradation, human infection-causing agents can find their way to the discarded human tissue, where they can thrive and then reinfect others. Such wastes must therefore be completely destroyed.
One method for destroying medical waste is incineration. While apparently both sterilizing and destroying the medical waste, the process has proved inadequate as a means to ensure total destruction of all pathogenic agents, including viruses. There is an inherent inability to achieve complete combustion or destruction of all viruses or other pathogenic agents before they find their way out the smoke stack, or flue, of the incinerator. "Cold pockets" can exist within the incineration chamber and flue through which viruses or other pathogens can escape unharmed from the incineration process. This is due to the interrelationship between the tremendous updrafts present in incinerator flues and the possibility that the chemical reaction dynamics necessary to completely destroy all viruses, bacteria, or other pathogens are inadequate to ensure complete destruction of the viruses or bacteria before they are carried up through the flue by the fast moving flue gases. Even if complete sterilization is achieved, incineration generally requires large inputs of fossil fuels.
With respect to other kinds of once living tissues, such as discarded animal or human corpses, the impending scarcity of available land for grave sites will severely inhibit the luxury of simply burying our dead in the future. In fact, many societies, both old and new, have customarily disposed of corpses in a manner that does not require the use of huge tracts of land. One such method is, of course, cremation. However, cremation, while generally effective, is analogous to the incineration method of destroying medical wastes and has each of its limitations, including the inability to achieve complete combustion of all inorganic materials, including viruses or other pathogenic agents, and the requirement of large energy inputs, usually in the form of fossil fuels.
Moreover, the environmental impact of the disposal of medical wastes or other once-living human or animal tissues should not be overlooked. Instead of incineration, some have attempted to first disinfect the infectious waste and then dispose of it in landfills which, as stated above, are in ever diminishing short supply. Moreover, such medical wastes must be specially disposed of to prevent environmental contamination, at least in part because of the aforementioned tendency of dead human tissues, even previously sterilized tissue, to harbor disease-causing bacterial or other pathogenic agents.
Because of the ever-increasing number of medical procedures and cures that are continuously being developed, the amount of medical wastes that will need to be disposed of every year will increase indefinitely. Moreover, the ever-increasing amount of biotechnical research and development being performed in order to find new cures for human or animal diseases is responsible for the creation of dangerous disease-causing agents that, if accidentally released into the environment, could be catastrophic to the health of humans or animals. Hence, the need to efficiently and completely disinfect these and the aforementioned medical wastes has become acute and will continue to increase into the future.
One recently developed method for disinfecting and destroying toxic medical wastes and other organic materials is to destroy them in situ within a land disposal site using extreme temperatures. For example, U.S. Pat. No. 5,181,795 to Circeo, Jr. et al., teaches a method for destroying biological wastes by drilling a series of holes into which the organic waste is to be disposed, inserting a plasma arc torch in each hole to pyrolyze, remediate, and vitrify (i.e., fuse) the waste materials, and then allowing the melted materials to cool down into essentially a chunk of glass. The drawbacks are the need for remote disposal sites and the requirement of large energy inputs, which are the same as for incineration.
U.S. Pat. No. 4,974,531 to Korenburg teaches methods and apparatus utilizing a fluidized bed for incinerating hazardous waste at temperatures from 1400.degree. F. to 1800.degree. F. Although this patent discloses that lower temperatures down to 300.degree. F. can be used to disinfect the infectious waste, Korenburg teaches that actual destruction of such wastes in the fluidized bed occurs at high temperature (1400-1800.degree. F.). Thus, Korenburg teaches yet another high temperature method for incinerating organic wastes, albeit using a fluidized bed to facilitate the incineration process. Also of interest is U.S. Pat. No. 4,308,806 to Uemura et al., which teaches the use of a fluidized bed incinerator operating at high temperatures (up to 1000.degree. C.) for burning various types of industrial waste.
Another unfortunate problem associated with the modern economy involves pollutants that are produced in internal combustion engines. For instance, diesel engines are widely used in industrial applications, in commercial trucking vehicles, and in personal automobiles. Diesel engines have contributed to much economic activity, but also are a major source of air pollution. Combustion products that are generated in diesel engines from the burning of diesel fuel are ordinarily released into the air. Some of the most harmful pollutants generated in diesel engines and other systems that are powered by carbon-containing fuel are carbon soot and other pollutants that result from incomplete combustion. Carbon soot includes particulates of unburned hydrocarbons and other carbonaceous particulates. These fine particulates contribute to respiratory ailments and urban air pollution.
In response to pollution caused by gasoline-powered internal combustion engines, catalytic converters have been developed to reduce the levels of incomplete combustion pollutants that are emitted into the environment. Catalytic converters are typically positioned in the exhaust system of an internal combustion engine to fully oxidize at least a portion of the exhaust gases. The complete combustion products, particularly carbon dioxide and water, are considered more environmentally acceptable than their incomplete combustion counterparts. Conventional catalytic converters contain palladium or platinum which facilitate oxidation of exhaust gases. However, the foregoing metals are relatively rare and expensive. Moreover, catalytic converters are easily damaged, and a non-functioning catalytic converter is not readily detectible without an analysis of the exhaust gases.
While catalytic converters have provided some measure of reduction of harmful incomplete combustion pollutants from gasoline-powered engines, diesel engines have been largely exempted on economic grounds from the increasingly stringent pollution standards applicable to gasoline-powered vehicles. This public concern has translated into an increase in political pressure and activity to strengthen emission standards for diesel engines. There is a possibility that emission guidelines will be imposed in certain states that are strict enough to make long-distance trucking of goods cost-prohibitive, or that may even be impossible to comply with using conventional pollution control devices.
In view of the foregoing, it would be a significant advancement in the art to provide methods and systems that would result in complete and reliable destruction of medical wastes, corpses, and other organic matter.
It would be a further advancement in the art if such methods and systems resulted in the complete and reliable destruction of medical wastes, corpses, and other organic matter at temperatures lower than combustion temperatures.
It would be an additional advancement in the art if such methods and systems completely and thoroughly destroyed the medical waste, corpse, or other organic matter in a catalytic manner in order to reduce or eliminate the generation of noxious gases or other environmental pollutants, as can be produced using high temperature incineration methods.
It would be yet another advancement in the art to provide systems and methods that could destroy organic matter at lower than combustion temperatures in order to reduce the need for fossil fuel energy inputs.
It would be a considerable advancement in the art to provide apparatus for carrying out such methods that were relatively small and portable and that could be stationed at a variety of locations within a hospital, research laboratory, or other situs where medical wastes, corpses, or other organic matter need to be destroyed without the possibility that dangerous viruses or pathogens could be released into the environment, particularly at a hospital or laboratory where sterile conditions are especially vital, or through the transport of such wastes to available landfill sites.
It would be a further advancement in the art to provide systems and methods for oxidizing incomplete combustion products from diesel engines and other systems that burn fossil fuels, thereby replacing conventional catalytic converters that use palladium, platinum or other expensive catalytic agents.
Finally, it would be yet another advancement in the art to provide apparatus for carrying out such methods of oxidizing incomplete combustion products that are relatively lightweight and that may be economically installed on a vehicle that is powered by a diesel engine or another internal combustion engine.
Such methods and systems for catalytically destroying organic materials as described above are disclosed and claimed herein.